A device that performs a tracking process that generates an automatic steering torque so that a steering angle of a vehicle becomes a target steering angle by using a power steering device that generates assist torque according to a steering operation of a driver as a driving support device for a vehicle is known.
In addition, in this type of device, while the tracking process is executed, it is proposed that the tracking process is regulated so that the vehicle can be steered according to the steering operation of the driver when the driver performs a so-called driver override steering operation (hereinafter also referred to as DOR) (refer to Japanese Patent Application Laid-Open Publication No. 2015-20604 (Patent Document 1), for example).
According to the proposed device, when the DOR occurs while the tracking process is being executed, a deviation of a steering angle caused by the DOR is canceled by the tracking process, so that the driver cannot steer the vehicle by the steering operation, and discomfort that the driver feels can be suppressed from occurring.
However, in the above proposed device, when the driver performs the steering operation while the wheels are being steered by the tracking process, there may be a difference in a steering reaction force with respect to the steering operation depending on an operation direction.
This is because a self-aligning torque (hereinafter also referred to as SAT) that tries to return the steering angle to 0 is generated when wheels for steering (hereinafter also referred to as steered wheels) are steered to the left or right from the neutral position of the steering angle 0 such as while the vehicle is turning.
That is, when the driver increase turning of the steering wheel in the right direction while the wheels are being steered to the right by the tracking process, for example, since the operation direction is opposite to the SAT, the steering reaction force becomes larger.
In contrast to this, when the driver return the steering wheel position back to the left, since the operation direction becomes the same direction as the SAT, the steering reaction force is reduced and so-called steering force loss occurs.
Therefore, according to the proposed device, when the driver performs the steering operation while the steering wheels are being steered to the left or the right from the reference position by the tracking process, the steering reaction force greatly differs depending on the operation direction, giving the driver a sense of discomfort.